Semiconductor devices are commonly found in modern electronic products. Semiconductor devices vary in the number and density of electrical components. Discrete semiconductor devices generally contain one type of electrical component, e.g., light emitting diode (LED), small signal transistor, resistor, capacitor, inductor, and power metal oxide semiconductor field effect transistor (MOSFET). Integrated semiconductor devices typically contain hundreds to millions of electrical components. Examples of integrated semiconductor devices include microcontrollers, microprocessors, charged-coupled devices (CCDs), solar cells, and digital micro-mirror devices (DMDs).
Semiconductor devices perform a wide range of functions such as signal processing, high-speed calculations, transmitting and receiving electromagnetic signals, controlling electronic devices, transforming sunlight to electricity, and creating visual projections for television displays. Semiconductor devices are found in the fields of entertainment, communications, power conversion, networks, computers, and consumer products. Semiconductor devices are also found in military applications, aviation, automotive, industrial controllers, and office equipment.
Semiconductor devices exploit the electrical properties of semiconductor materials. The atomic structure of semiconductor material allows its electrical conductivity to be manipulated by the application of an electric field or base current or through the process of doping. Doping introduces impurities into the semiconductor material to manipulate and control the conductivity of the semiconductor device.
A semiconductor device contains active and passive electrical structures. Active structures, including bipolar and field effect transistors, control the flow of electrical current. By varying levels of doping and application of an electric field or base current, the transistor either promotes or restricts the flow of electrical current. Passive structures, including resistors, capacitors, and inductors, create a relationship between voltage and current necessary to perform a variety of electrical functions. The passive and active structures are electrically connected to form circuits, which enable the semiconductor device to perform high-speed calculations and other useful functions.
Semiconductor devices are generally manufactured using two complex manufacturing processes, i.e., front-end manufacturing, and back-end manufacturing, each involving potentially hundreds of steps. Front-end manufacturing involves the formation of a plurality of die on the surface of a semiconductor wafer. Each die is typically identical and contains circuits formed by electrically connecting active and passive components. Back-end manufacturing involves singulating individual die from the finished wafer and packaging the die to provide structural support and environmental isolation.
One goal of semiconductor manufacturing is to produce smaller semiconductor devices. Smaller devices typically consume less power, have higher performance, and can be produced more efficiently. In addition, smaller semiconductor devices have a smaller footprint, which is desirable for smaller end products. A smaller die size may be achieved by improvements in the front-end process resulting in die with smaller, higher density active and passive components. Back-end processes may result in semiconductor device packages with a smaller footprint by improvements in electrical interconnection and packaging materials.
FIG. 1 shows a conventional semiconductor wafer 10 with a plurality of semiconductor die 12 formed on the wafer separated by saw streets 14. An insulating or dielectric layer 16 is formed over active surface 18. An electrically conductive layer 20 is formed over insulating layer 16. Conductive layer 20 operates as contact pads for electrical connection to external circuits. An insulating or passivation layer 22 is formed over insulating layer 16 and conductive layer 20.
FIG. 2 illustrates a portion of conventional semiconductor die 12. A plurality of vias is formed through the base semiconductor material of die 12 and insulating layer 16. An insulating material is first formed on the sidewalls of the vias as an insulating ring 24. After forming insulating ring 24, the remaining via area is then filled with electrically conductive material over insulating ring 24 to form z-direction vertical conductive through silicon vias (TSV) 26.
FIGS. 3a-3d illustrates another conventional conductive TSV with an insulating ring. In FIG. 3a, a plurality of vias 28 is formed through the base semiconductor material of die 12 and insulating layer 16. An insulating material is first deposited into vias 28 to form insulating ring 30, as shown in FIG. 3b. In FIG. 3c, vias 32 are cut to remove the base semiconductor material within or inside insulating ring 30 and insulating layer 16 down to conductive layer 20. After forming insulating ring 30, the remaining via area 32 is then filled with electrically conductive material to form z-direction vertical conductive TSV 34, as shown in FIG. 3d. Conductive TSV 34 are electrically connected to conductive layer 20.
In each case, the insulating ring is deposited prior to the conductive TSV. Consequently, the insulating material accumulates on the exposed conductive layer 20 during deposition. The insulating material must be removed or cleaned from the TSV contact area of conductive layer 20 prior to filling the vias with the conductive material to ensure good electrical contact. The process of removing insulating residue from the TSV contact area of conductive layer 20 is time consuming and adds manufacturing cost. Failure to properly remove insulating layer 24 from the TSV contact area of conductive layer 20 causes high contact resistant and defects in semiconductor die 12.